At fifteen, Remus Lupin's world is full of edges. There's the edge of the bed that he clings to, retching onto the floor, the room swirling and whirling around him. His torso tenses and tries to turn itself inside out, painful shudders and lurches, until there is nothing left but spit and stomach acid.
Sirius lets out a snore from the next bed, his leg twitching with the adventures of sleep. Remus breathes in the cool, dry air and rolls onsto his back, too tired to throw up anymore. There will be plenty of time for that in the morning.
"Easy, easy," a voice says, and Remus realises that James is beside him, pushing his sweaty hair back, laying a damp flannel on Remus's forehead. He hadn't known James was there. He'd thought he was alone.
James leans in close, his spectacles catching the moonlight. "Silly wanker," he says quietly. Remus is too spent to say anything to that, so he closes his eyes and waits for unconsciousness to take him. As he drifts off, he could swear he feels fingernails sliding over his scalp in long, soothing motions.
At seventeen, Remus Lupin's world is full of edges. He's standing quite literally on the edge of the rooftop, his tip-toes dangling over. He breathes deeply, letting the warm night air and the smell of wet grass drown him. There's a pleasant hum of insects and the distant sound of waves lapping against the shore of the lake, but mostly, it is quiet.
At his back there is an enormous, jutting chimney, and behind that his friends are waiting for him, but he can't hear them. He needs this sometimes, the still quiet danger and the moment to think, to really think about what he is doing at that moment, because if he doesn't he will fall and never think again. The tension brings clarity, and the clarity brings relief (because clarity is such a rare and precious thing at seventeen, at sixteen, at fifteen.)
"If you fall, don't expect me to mount a heroic rescue effort."
Remus smiles without turning around. "That's alright. If I survive, I'll tell everyone you shoved me," he says good-naturedly.
James is warm and solid behind him, and though their bodies aren't quite touching, Remus can feel the muggy heat of his breath on the back of his neck. They stand there, unmoving and silent, staring down at the ground so far below.
Suddenly, there is an arm around Remus' waist, tugging him back from the edge, one, two, three steps, until he feels them slam into the broad side of the chimney. There is a moment of stillness, and Remus can feel their hearts beating in time with the insects' cries for company. The only movement is a warm, damp hand sliding gracelessly beneath Remus' t-shirt, flat against the hollowed plain of his abdomen.
"What are—" Remus whispers, but there are fingers dipping into the waistband of his trousers, brushing his cock beneath a thin layer of cotton.
"Tell me to stop," James says against his ear, his voice dangerous and cocky. The air rushes from Remus' lungs with a sound like ahh, and he presses into James hand unintentionally. Fingers creep into his pants and he feels James' palm slides gently against his erection before taking hold, tight and blisteringly hot. The only sound is the bugs and the wind and the slip-sticky slide of warm, wet flesh, and Remus digs his bitten-down nails into James' arm and lets his head fall back against James' shoulder.
James presses open-mouthed, sucking kisses to Remus' sweaty neck.
"Would you two stop necking and get your arses over here?" Sirius shouts from the other side of the chimney, his voice distant and muffled by ancient bricks and mortar.
"Coming, love!" James yells back, and Remus can practically hear the cheeky look on his face, because Remus is coming, and it's fantastic, and his knees give out and his cock almost hurts it's so fucking good.
The next thing he notices, James is holding him up, his arm like a clamp around Remus' ribcage. "Shirtlifter," he mutters affectionately into Remus' hair.
At nineteen, Remus Lupin's world is full of sharp edges. The edge of the bureau is digging into his back and James' teeth are sharp against his mouth. Fast, confident hands pull Remus' shirt over his head, breaking their mouths apart for all of two seconds, which is fine because it gives them a chance to crash together again.
James presses his erection into Remus's hip and mutters with soft, red lips "Moony, would you…?" He trails off, his tongue tracing the bone of Remus's shoulder.
Remus nods silently, spinning them around and slamming James backwards. Neither of them is sure when it got like this, so casual and automatic but still no less fervent and secret. But it is what it is, and Remus tugs at James' flies before kneeling down and sucking gently on the tip of his cock.
The dull thump of James' head as it falls against the bureau echoes through the empty room. It contains only three pieces of furniture and a bare mattress in the corner, but they don't go near the mattress because that is where he and Lily will sleep, and what they do can never have anything to do with Lily. It's not fair to her, and it's even less fair to Remus.
With his tongue, he traces all the sensitive places on James' prick, the ones that make him shiver and the ones that make him thrust into Remus's mouth. He tastes like sweat and smoke and the hot wind atop Gryffindor tower. When James comes, his fingers twist in Remus' hair, holding him in place, and Remus swallows because he can't not.
At twenty-one, Remus Lupin's world is made of edges. He leans over the edge of the crib, staring down at the sleeping lump of blankets that has turned all their lives on their heads. James closes the door behind him and sidles up to Remus, his hands hard on Remus' hips and his teeth gentle on Remus' neck.
"Prongs, don't—"
"Shhh, she's gone. She'll be out for hours. Baby's asleep," James says, his voice husky and dark.
"The baby, the baby," Remus repeats, unsure what he means but desperate to say it. James licks along the shell of Remus' ear and sighs, his bulge pressing hard and hot against the back of Remus' thin shirt.
"C'mon," he mutters. Remus starts to object, but it never matters. They'll do it because they always do, and habits die hard and all that bollocks.
They fuck on the floor and James groans Remus' name as his hips slam into him over and over and over. The baby wakes up, makes soft cooing sounds in his crib, but they don't stop. When Remus comes, he closes his eyes, wondering how something this good became so terrible, and whether he is a fool to question it.
James comes inside him, his hands tight on Remus' shoulders, his breath loud and broken.
The baby shrieks and James pulls away so fast Remus feels his body collapse in on itself. He looks up and sees James, trousers undone, hair at new and interesting angles, cradling the baby against his shoulder, swaying slowly in the dark.
Remus feels like he might be sick, but he knows that this time James won't be there to make it better. And he realises in that moment that there are no edges left to go over.